Commercial and residential refrigeration units, such as refrigerators, air conditioners, heat pumps and other small air-conditioning and refrigeration units use chlorofluorocarbons (CFC's) as a standard heat-transfer media. For many years, when a refrigeration unit needed servicing, it was common practice in the industry to simply release the refrigerant to the atmosphere. That practice is no longer acceptable, nor is it responsible to abandon CFC-containing equipment because it would eventually leak out. It has become increasingly desirable to service CFC-containing units in a manner which prevents the loss of CFC's to the atmosphere or the environment, and to remove CFC's from non-serviceable units before the refrigerant leaks out.
Generally, when servicing units, it is both cost effective and environmentally responsible to recover refrigerant from the unit prior to servicing. After a unit is opened and serviced, it must then be evacuated of all moisture and/or other contaminants prior to recharging the unit with refrigerant. Failure to properly evacuate a unit prior to recharging can result in damage to the compressor, and/or freezing up of refrigerant lines when in use.
In one known system, a refrigerant recovery apparatus having a compressor, a condenser and a refrigerant storage container is used to recover refrigerant from a unit to be serviced. Due to limitations on the vacuum pressure which can be generated by the recovery compressor, the unit to be serviced cannot be fully evacuated prior to recharging using a recovery unit alone. The recovery apparatus is then generally disconnected from the unit then being serviced, and a vacuum pump is connected to the unit to draw a vacuum on the unit to fully evacuate the system.
One disadvantage of this type of system is the need to use two different pieces of equipment, one for recovering refrigerant from the system and a separate vacuum pump for completely evacuating the system.
Another known system provides a refrigerant recovery, purification and recharging system which includes a compressor driven by a first motor connected by a solenoid valve to the container to be evacuated, and a separate vacuum pump driven by its own motor, also connected by solenoid valves to the unit to be evacuated. The refrigerant is first recovered by setting the solenoid valves such that the compressor draws the refrigerant from the unit, compresses the refrigerant prior to passing the refrigerant through a condenser, and on to the recovery container. After the refrigerant has been recovered to a level acceptable by the EPA, the system is evacuated by a separate evacuation process utilizing the vacuum pump.
One drawback of this system is that both the compressor and the vacuum pump have separate motors, and although there is some convenience in having recovery and evacuation capabilities in a single piece of equipment, the weight and size of the unit are increased by the separate motors.
The present invention is a result of observation of the problems associated with the prior art devices, and efforts to solve them.